Saturn’s Polar Cyclones a Mystery

NASA’s Cassini spacecraft has taken new pictures showing a giant cyclone at Saturn’s north pole and its south pole, the latter apparently powered by Earth-type storm patterns.

The characteristics of these cyclones differs from Earth-based cyclones in interesting ways.

The north pole cyclone is only visible in the near-infrared wavelengths due to winter in that region of Saturn. At these wavelengths, seven times greater than that of visible light, the clouds deep inside Saturn’s atmosphere are only seen in silhouette against the background radiation of Saturn’s internally generated heat.

An infrared map of the north pole of Saturn has been created showing features as small as 120 km (75 mi) visible. The whirlpool-like cyclone there is rotating at 530 km/hr (325 mph), more than twice as fast as the highest winds measured in cyclones on Earth.

This cyclone is surrounded by a honeycombed-shaped hexagon, which itself does not seem to move while the clouds within it whip around at high speeds, also greater than 500 km/hr (300 mph). Neither the fast-moving clouds inside the hexagon nor this new cyclone seem to disrupt the six-sided hexagon.

Hurricanes on Earth are fueled by the ocean’s heat and water while Saturn’s cyclones have no body of water at their bases as Saturn’s hurricanes are locked to the planet’s poles, whereas terrestrial hurricanes drift across the ocean.

Just as condensing water in clouds on Earth powers hurricane vortices, the heat released from the condensing water in Saturn’s thunderstorms deep down in the atmosphere may be the primary power source energizing the vortex.

At the southern pole, the new infrared images of the pole, under the daylight conditions of southern summer, show the entire region is marked by hundreds of dark cloud spots.

The clouds, like those at the north pole, are likely composed of ammonium hydro-sulfide with possibly a mixture of other materials from below. Conversely, most of the hazes and clouds seen on Saturn are believed to be composed of ammonia, which condenses at higher and more visible altitudes.